Telephone-receiver.



G; MoMEBN-- TELEPHONE RECEIVER. i APPLICATION FILED APB. 28, 1910.

I 1,027,494, Patentea'may 28,1912.

mum v' sAMuELe. McMEN, or. FRANCISCO, CALIFORNIA, AssIeNOn rIo McivIEN aMILLER, or CHICAGO, ILLINOIS,

' l -To all whom t may concern.:

Be it 'known that I, SAMUEL a citizen of the UnitedStates of America anda resident of San'Francisco, county of San Francisco, and -State ofCalifornia, have invented anew anduseful Improve ment inTelephone-Receivers, of which the following is a specification.

My 4invent-ion pertains to telephone ref c'eivers, in common battery orcentralized energy In such systems, in order that the 'substationapparatus may be of the simplest type, it is convenient tok permit thecurrent which iows .upon the telephone line during conversation to flowthrough the telephone receiver as well. This-is .objectionable when,thereceiver is of the ordinary construction,

comprising in nearly all and many devices,

circuit wiring external cases apparatus and to the receiver itself, havebeen devised, and

- 'sdnme otthem have been used -successfully, tOv

prevent the undesirable elects produced by the current flowing throughthel receiver. VIn some of these devices, direct Current is preventedfrom flowing through the receiver, and in Others itis greatly reduced.

.An element in the construction of the usual type of receiver is thepermanent mag net. This in `my improved receiver vIreplace by anelectromagnet,

In order that the vdirect current of the telephone line may low throughthe' re' c eiver, and that 'the' simpliedcircuits possible under such aconditionl may be used, I make a receiver havinga speech-currenttranslating coil andhaving an electromagnetic tield coil, and I thenprovide means within 'the receiver case for separating the currents ofthe telephone line into-direct currents, the path of which includes thefield magnet coil; and'speech currents, the

.path of whichincludesthe diaphragmactuating or speech-current'translating coll.

In the drawings which accompany and form a part'of thisspecication-Figure 1.

shows a sectional elevation through my improved receiver; Fig. 2 showsan enlarged section of the upper part of my receiver; Fig. 3 shows aplan view of the under side of the magnetic devices; Fig. 4 showsdiagrammatically the circuit arrangement;

and particularly to receivers for use it, thus holding it securely inplace. terminals of the condenser -are arrangedl upon the end nearer thelarge end of the l lwasher -sir'ed initial magnetic strength at theupper.l

end-of the core' 9.' Thus, the initial mag- 95 A CoPAR'INERsHIr.-

' Speciication'of Letters `Patent; i vlateinted May-28,1912.'Aplilicaton fneaaprn 28,-1'910. seriarNq. '558,238'

Iig.- 5` shows diagrammatically 'an alternative form'of my device, usingone coil in-I` 55l stead of two. Like figures refer the several views. l

The receiver case is composed of three in body 1, which may-be a castingory a turned piece, is an' annular'internal rib 'l'.

A rolled condenser 4 is rolled upon la fiber tube 5, thus making atubular condenser'. This condenser isinserted into' the receiver 65 case-from the small end, andy is'clamped-by' the end piece 2, whichisscrewed down upon The receiver.` The electromagnetic system'of thereceiver comprises a pressed magnetic cup, two helices containedAthereby, a magnetic core, a magnetic washer and a magnetic diay`-Terminals are mounted "upon the phragm.

exterior ofthe magnetic cup, andthe coils,

core and'washer are mounted within thecup, the diaphragm being placedover the mouth hereof, and both cup and diaphragm, 8O I clampe between'parts 1 and 3 of'thereceiver, all as shown lclearly in the drawings.Coil 6 is the field coil of the receiver, `which that 'constant ,magnetism 4required.- to place stress. The magnetic washer '7, together withthe smaller cylinder 8 of the magnetic 1 cup," form a magnetic circuitvery nearly closed, and give a vervhigh inductanc'e value to the coil 6,and 'i atfthe ysame time 90 producethe' required'magnetism at the uppei`end of the core 9`. Thedimensions of 7 may be such as to permit thedenetic strength. may be controlled in the design and manufacture.

' The coil 18 is 'the actuating coil of the de-v vice and is made of iatform and located in close proximity to the diaphragm, so that 12 and13,' which servev as a `means for c'on- 105 necting the coils andcondenser in circuit, as

to like parts throughout i the diaphragm under' an initial 85 i showninFig. `4. One terminal of coil 6 is ductors 20 and 21 of the receiverpassthrough'the receiverin two paths, the rst brought out through thecup8 and soldered to the terminal 11; one terminal -of the oo ndenser 4is connected to terminal 11 ;while one terminalv of coil 18 is ledthrough the magnetic cup and connected to the terminal .13, theremaining terminal of condenser 4 being also connected-to terminal 13;and the remaining terminals of coils 18 and 6 are 4led through the cup 8and connectedto terminal. 12. The circuits -of the device are clearlyshown in Fig. 4. The incoming conof which includes only the eld winding6 in the shape of a long, slender cylinder about the core, and thesecond of which-includes condenser 4 and the winding 18 in the form of avery short cylinder of comparatively large diameter..

Because of the fact relatively narrow and-is in a` path carrying directcurrents, some of the lines of-force generated' by the current throughthat winding will closethrougli the magnetic-washer 7 and some willclose'through the center of 4the diaphragm, but in general it isintended that the magnetic circuit of the winding 6 is notformed whollythrough the diaphragmL 30 The winding 1&8 carries speech currents, andthis windingis made relatively thin, so that the diaphragm and thebottom of the shallow portion of the cup. are separated by'I but asmalldistance, thus` not concentrating lthe forces at the center of thediaphragm.

With sucha construction, even if the'centrai core fwere to be "removed,there would f renain a tendencyfor the two sides of the .magneticcircuit sodescribed to draw to# gether under the influence 'of anycurrent,

other magnetic conditions being'absent; and while the centerfof thediaphragm is 'free to move and vis under the influence of a greaterforce to make it move, there is such a' tenddency in some degree,throughout the area occupiedby thewinding 18, f f

In all forms oit-telephonel receivers which.

have come into general commercial use, the

diaphragm is influenced at or near its centeronly, whether there be bothor onlyA one of. the poles presentedl to'that"poi tion kof it. f

.l While my present invention does concentrate the forces at about thefcente'r ofthe hat the winding 6 is currents Aof higher frequency, afterthey have frequencies and lower'amplitudes. Whileitf is of importancethat-transmission lines be so constructed `as to. reduce the lossesl dueto attenuation and distortion, 1t is also ini- .portant -soto constructthe receiving device as to be lresponsive to what remains of the beensubject to such losses as have occurred in the line. .l "r A yLArelation exists between a diameter of the'reciver diaphragm and thefrequency'of voice current to which the receiver-is most readilyresponsive.

inches or more in diameter and a cup of similar size, I- do not considerit essential that so great diameters be used.- Satisfac`- torycommercial results are secured by dia While, therefore, my 4drawingshows in scale -a diaphragm of two phragm and cup diametersof the orderof one inch. 'Such a modification of the general magnitude of theseparts should be ac' companied-by a similar modification in the shell ofthe winding 6, so that the winding 6 may, in general, be long andnarrow, while l the winding 18 may, in general, be wide and thin.

Fig. 5` illustrates an alternative form of 4my device, in which apermanent magnet is n' utilized instead of an electromagnet, and directcurrents are .prevented from passing -through the actuating coil bymeans ofthe Lcondenser 4 retained within theha'ndle of ithe receiver, asdescribed in the foregoing l and characteristics asdescribed.

Having thus described my invention, what specification, the condenser inthis form of my device being of the same general shape I claim as newand desire to se'cure'by United States Lettersipatent is 1. In atelephone receiver, a case of'three parts; an internal annular rib uponthe body j p art of said case; a condenser between said l rib and thesecond-of said parts, forming a `cap upon one end of the receiver; .andan .electromagnetic system clamped between .said-receiver body andthethird of said f parts, forming a cap upon the other end of the receiver.

2. In "a' telephone receiver, a removable end cap; an internal abutmentmember; and a condenser within the receiver, and reftainedv by said ca pandsaid abutment member.

3. In a telephone receiver, a case; a tubularcondenser within said case;an electromagnetic system within said case; and a flexible conductingcord passing through the i middle of said condenser and connecting tosaid electromagnetic system andto said condenser. c

4. In a telephone receiver, 'a case; a magnetic cup; a diaphragm closingthe lmouth of said cup; a helix within said cup; a condenser within saidcase, and connected electrically with saidwhelix.

5. Inv a telephone receiven'a magnetic oup Signed by me at SanFrancisco, county of in the shape of two coaxal'cylindroal oham- ASanFranolsoo and State of California, in bers; a magnetic' diaphragmclosing the. the presence of two witnesses.

mouth of said cup; a magnetic core in the SAMUEL G. MCMEEN. 5 axis ofsaid cup; and a -washer upon said` `Witnesses:

core, located at or near the division plane of GERTRUDE COHEN,

said two coaxial cylindrical chambers. Y FREDERICK L. BAER.

